Substituted piperazine diones and polymeric compositions stabilized thereby

ABSTRACT

Substituted piperazine diones are stabilizers for synthetic polymeric materials normally subject to deterioration caused by ultraviolet light. The compounds are prepared by the alkylation reaction between a substituted piperazine dione and an organic halide. Polymeric compositions containing these stabilizers may also contain a hindered phenolic compound. A typical embodiment is 15,15&#39;-dodecamethylenebis(7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione).

RELATED APPLICATION

This is a divisional of application Ser. No. 391,200 filed on Aug. 24,1973, now U.S. Pat. No. 3,928,357 which is a continuation-in-part ofapplication Ser. No. 237,982, filed Mar. 24, 1972, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to the stabilization of organic material normallytending to deteriorate. In particular, the invention relates to theprotection of synthetic polymers against the harmful degradativeeffects, such as discoloration and embrittlement caused by exposure tolight, especially ultraviolet light.

It is known that actinic radiation, particularly in the near ultravioletregion, has a deleterious effect on both the appearance and propertiesof organic polymers. For example, normally colorless or light coloredpolyesters yellow on exposure to sunlight as do such cellulosics ascellulose acetate. Polystyrene discolors and cracks, with accompanyingloss of its desirable physical properties when exposed to actinic light,while vinyl resins, such as polyvinyl chloride and polyvinyl acetatespot and degrade. The rate of air oxidation of polyolefins such aspolyethylene and polypropylene is materially accelerated by ultravioletlight.

It has been proposed to stabilize polymeric materials againstultraviolet light deterioration by the use of various types ofultraviolet absorbers. Thus, U.S. Pat. No. 3,004,896 discloses for thispurpose 2(2-hydroxyphenyl)benzotriazole derivatives, while U.S. Pat. No.3,189,630 discloses certain metal salts of hydroxybenzoic acids whichare useful as actinic stabilizers in synthetic polymers.

DETAILED DISCLOSURE

The present invention is directed to a class of ultraviolet lightstabilizers which consist of a compound of the formula ##STR1## WHEREINR¹ and R² are independently of each other methyl or ethyl or togetherwith the carbon to which they are bound form a cyclopentyl or cyclohexylring, which is unsubstituted or substituted with a methyl group;

n is an integer of from 1 to 3; when n is 1, R³ is an alkyl group offrom 1 to 20 carbon atoms or a benzyl group; when n is 2, R³ is analkylene group of from 1 to 20 carbon atoms, a p-xylylene group or analkyl substituted p-xylylene group, of the formula ##STR2## wherein R⁴,R⁵, R⁶ and R⁷ is hydrogen or lower alkyl group containing from 1 to 5carbon atoms;

when n is 3, R³ is a 1,3,5-mestiylene group or a 2,4,6-alkyl substitutedmesitylene group, of the formula ##STR3## wherein R⁸, R⁹ and R¹⁰ arehydrogen or lower alkyl, containing from 1 to 5 carbon atoms.

By the term alkyl as represented by R¹ and R² is intended methyl orethyl, with methyl being the preferred substituent. Representative ofthe cycloalkyl groups are cyclohexyl, cyclopentyl, 2-methyl, 3-methyland 4-methylcyclohexyl, and 2-methyl and 3-methylcyclopentyl. Thepreferred cycloalkyl groups are cyclohexyl and 2-methylcyclohexyl.

This invention also relates to compositions of matter which arestabilized against ultraviolet light deterioration which comprises asynthetic organic polymer normally subject to ultraviolet deteriorationcontaining from about 0.005% to 5% by weight of the polymer of thecompounds of formula I and preferably from 0.01% to 2% by weight.

The piperazine dione derivatives as represented by formula I can be usedin combination with other light stabilizers such as2-(2-hydroxyphenyl)benzotriazoles, 2-hydroxybenzophenones, nickelcomplexes, and benzoates.

The stabilizers of this invention are suitable for the protection ofmany synthetic polymers from the deleterious effects of light.Homopolymers, copolymers, and mixtures thereof are embraced within thescope of substrates which may be stabilized with the stabilizers of thisinvention, along which may be mentioned, polystyrene and includinghomopolystyrene and copolymers with acrylonitrile and/or butadiene;vinyl resins formed from the polymerization of vinyl halides or fromcopolymerization of vinyl halides with unsaturated polymerizablecompounds, for example, vinyl esters, α,β-unsaturated acids,α,β-unsaturated esters, and unsaturated hydrocarbons such as butadienesand styrene; poly-α-olefins such as high and low density polyethylene,cross-linked polyethylene, polypropylene, poly(4-methyl-pentene-1),polybutene-1, and the like including copolymers of poly-α-olefins suchas ethylene-propylene copolymers, and the like; polybutadiene;polyisoprene; polyurethanes such as are prepared from polyols andorganic polyisocyanate; polyamides such as hexamethylene-adipamide;polyesters such as polymethyleneterephthalates; polycarbonates such asthose prepared from bisphenol-A and phosgene; polyacetals; polyethyleneoxide; and polyacrylics such as polyacrylonitrile; polyphenyleneoxidessuch as those prepared from 2,6-dimethylphenol and the like.Particularly preferred polymers for the compositions of this inventionare those normally solid polymers of alpha-olefins having up to 3 carbonatoms, e.g., ethylene-propylene and their copolymers.

The stabilized polymers of the present invention have utility in thenormal uses for which plastics are employed and are particularly usefulfor film and fiber. Compounds of this invention may be incorporated inthe polymeric substance during the usual processing operations, forexample, by hot milling, the composition then being extruded, pressed,blow molded or the like into films, fibers, filaments, hollow spheresand the like. Where the polymer is prepared from a liquid monomer as inthe case of styrene, the stabilizer may be dispersed or dissolved in themonomer prior to polymerization or curing.

In addition to the actinic stabilizers described, the plasticcompositions may contain other additives such as plasticizers, pigments,fillers, dyes, glass or other fibers, thermal antioxidants, and thelike. For example in most applications, it is desirable to incorporateinto the resin composition, sufficient thermal antioxidants to protectthe plastic against thermal and oxidative degradation. The amount ofantioxidant required will be comparable to that of the actinicstabilizer. Namely, from about 0.005% to 5% and preferably from 0.01% to2% by weight. Representative of such antioxidants are phosphite esters,such as triphenylphosphite and dibutylphosphite and alkyl arylphosphitessuch as dibutylphenylphosphite, and the like.

The best results are obtained with the preferred class of thermalantioxidants, the hindered phenols. These compounds have been found toprovide the best thermal stabilization with the least discoloration inthe compositions of the invention. Typical of these phenolicantioxidants include the following:

1. Phenolic compounds having the general formula

    Q--(CH.sub.2).sub.w --A

wherein

Q is ##STR4## A is -- CR(COOR")₂ ##STR5## R is hydrogen or lower alkylR' is lower alkyl

R" is alkyl group having from 6 - 24 carbon atoms

w is an integer from 0 to 4.

Illustrative examples of the compounds shown above are

di-n-octadecyl α-(3,5-di-t-butyl-4-hydroxybenzyl)malonate

di-n-octadecyl α-(3-t-butyl-4-hydroxy-5-methyl-benzyl)malonate which isdisclosed in the Netherlands Patent No. 6,711,199, Feb. 19, 1968

di-n-octadecyl-α,α'bis-(3-t-butyl-4-hydroxy-5-methylbenzyl)malonatewhich is disclosed in the Netherlands Patent No. 6,803,498, Sept. 18,1968.

2. Phenolic compounds having the general formula

    Q--R

illustrative examples of the compounds shown above are

2,6-di-t-butyl-p-cresol

2-methyl-4,6-di-t-butylphenol and the like.

3. Phenolic compounds having the formula

    Q--C.sub.w H.sub.2w --Q

2,2'-methylene-bis(6-t-butyl-4-methylphenol)

2,2'-methylene-bis(6-t-butyl-4-ethylphenol)

4,4'-butylidene-bis(2,6-di-t-butylphenol)

4,4'-(2-butylidene)-bis(2-t-butyl-5-methylphenol)

2,2'-methylene-bis[6-(1-methylcyclohexyl)-4-methylphenol

and the like.

4. Phenolic compounds having the formula

    R--O--Q

illustrative examples of such compounds are

2,5-di-t-butylhydroquinone

2,6-di-t-butylhydroquinone

2,5-di-t-butyl-4-hydroxyanisole

5. Phenolic compounds having the formula

    Q--S--Q

illustrative examples of such compounds are

4,4'-thiobis-(2-t-butyl-5-methylphenol)

4,4'-thiobis-(2-t-butyl-6-methylphenol)

2,2'-thiobis-(6-t-butyl-4-methylphenol)

6. Phenolic compounds having the formula ##STR6##

Illustrative examples of such compounds are

octadecyl-(3,5-dimethyl-4-hydroxybenzylthio)-acetate

dodecyl-(3,5-di-t-butyl-4-hydroxybenzylthio)-propionate

7. Phenolic compounds having the formula ##STR7## wherein T is hydrogenR or Q as defined above.

Illustrative examples of such compounds are

1,1,3-tris(3,5-dimethyl-4-hydroxyphenyl)-propane

1,1,3-tris(5-t-butyl-4-hydroxy-2-methylphenyl)-butane

1,1,5,5-tetrakis-(3'-t-butyl-4'-hydroxy-6'-methylphenyl)-n-pentane

8. Phenolic compounds having the formula ##STR8## wherein B¹, B² and B³are hydrogen, methyl or Q, provided that when B¹ and B³ are Q then B² ishydrogen or methyl and when B² is Q then B¹ and B³ are hydrogen ormethyl.

Illustrative examples of such compounds are

1,4-di(3,5-di-t-butyl-4-hydroxybenzyl)-2,3,5-tetramethylbenzene

1,3,5-tri(3,5-di-t-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene

9. Phenolic compounds having the formula ##STR9## wherein Z is NHQ,--S--D or --O--Q D is alkyl group having from 6 - 12 carbon atoms or--(C_(w) H_(2w))--S--R"

Illustrative examples of such compounds are

2,4-bis-(n-octylthio)-6-(3,5-di-t-butyl-4-hydroxyaniline)-1,3,5-triazine

6-(4-hydroxy-3-methyl-5-t-butylanilino)-2,4-bis-(n-octylthio)-1,3,5-triazine

6-(4-hydroxy-3,5-dimethylanilino)-2,4-bis-(n-octylthio)-1,3,5-triazine

6-(4-hydroxy-3,5-di-t-butylanilino)-2,4-bis-(n-octylthioethylthio)-1,3,5-triazine

6-(4-hydroxy-3,5-di-t-butylanilino)-4-(4-hydroxy-3,5-di-t-butylphenoxy)-2-(n-octylthio)-1,3,5-triazine

2,4-bis(4-hydroxy-3,5-di-t-butylanilino)-6-(n-octylthio)-1,3,5-triazine.

The above phenolic triazine stabilizers are more fully described in U.S.Pat. No. 3,255,191.

10. Phenolic compounds having the formula ##STR10## wherein Z' is--O--Q, --S--D or --S--(C_(w) H_(2w))--SD

Illustrative examples of such compounds are

2,3-bis-(3,5-di-t-butyl-4-hydroxyphenoxy)-6-(n-octylthio)-1,3,5-triazine

2,4,6-tris-(4-hydroxy-3,5-di-t-butylphenoxy)-1,3,5-triazine.

6-(4-hydroxy-3,5-di-t-butylphenoxy)-2,4-bis-(n-octylthioethylthio)-1,3,5-triazine

6-(4-hydroxy-3-methylphenoxy)-2,4-bis-(n-octylthio)-1,3,5-triazine

6-(4-hydroxy-3-t-butylphenoxy)-2,4-bis-(n-octylthioethylthio)-1,3,5-triazine

6-(4-hydroxy-3-methyl-5-t-butylphenoxy)-2,4-bis-(n-octylthio)-1,3,5-triazine

2,4-bis-(4-hydroxy-3-methyl-5-t-butylphenoxy)-6-(n-octylthio)-1,3,5-triazine

2,4,6-tris-(4-hydroxy-3-methyl-5-t-butylphenoxy)-1,3,5-triazine

6-(4-hydroxy-3,5-di-t-butylphenoxy)-2,4-bis-(n-octylthiopropylthio)-1,3,5-triazine

6-(4-hydroxy-3,5-di-t-butylphenoxy)-2,4-bis-(n-dodecylthioethylthio)-1,3,5-triazine

2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-butylthio-1,3,5-triazine

2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(n-octadecylthio)-1,3,5-triazine

2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(n-dodecylthio)-1,3,5-triazine

2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(n-octylthiopropylthio)-1,3,5-triazine

2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(n-octylthioethylthio)-1,3,5-triazine

2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(n-dodecylthioethylthio)-1,3,5-triazine.

The above phenolic triazine stabilizers are more fully described in U.S.Pat. No. 3,255,191.

11. Phenolic compounds having the formula

    [Q--C.sub.z H.sub.2z --COO--C.sub.z H.sub.2z ].sub.p R'"-(R)4-p

wherein p is an integer from 2 to 4 and R'" is a tetravalent radicalselected from

aliphatic hydrocarbons having from 1 to 30 carbon atoms.

aliphatic mono and dithioethers having from 1 to 30 carbon atoms

aliphatic mono and diethers having from 1 to 30 carbon atoms and

z is an integer from 0 to 6.

Illustrative examples of such compounds are

Sub-class I

n-Octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate

n-Octadecyl 2-(3,5-di-t-butyl-4-hydroxyphenyl)-acetate

n-Octadecyl 3,5-di-t-butyl-4-hydroxybenzoate

n-Hexyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate

n-Dodecyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate

Neo-dodecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate

Dodecyl β-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate

Ethyl α-(4-hydroxy-3,5-di-t-butylphenyl)-isobutyrate

Octadecyl α-(4-hydroxy-3,5-di-t-butylphenyl)-isobutyrate

Octadecyl α-(4-hydroxy-3,5-di-t-butylphenyl)-propionate

Sub-class II

2-(n-octylthio)ethyl 3,5-di-t-butyl-4-hydroxybenzoate

2-(n-octylthio)ethyl 3,5-di-t-butyl-4-hydroxy-phenylacetate

2-(n-octadecylthio)ethyl 3,5-di-t-butyl-4-hydroxyphenylacetate

2-(n-octadecylthio)ethyl 3,5-di-t-butyl-4-hydroxybenzoate

2-(2-hydroxyethylthio)ethyl 3,5-di-t-butyl-4-hydroxybenzoate

2,2'-Thiodiethanol bis(3,5-di-t-butyl-4-hydroxyphenyl)acetate

Diethyl glycol bis-[3,5-di-t-butyl-4-hydroxyphenyl)propionate]

2-(n-octadecylthio)ethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate

2,2'-Thiodiethanol-bis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate

Stearamido N,N-bis-[ethylene3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]

n-Butylimino N,N-bis-[ethylene3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]2-(2-stearoyloxyethylthio)ethyl3,5-di-t-butyl -4-hydroxybenzoate

2-(2-hydroxyethylthio)ethyl7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate

2-(2-stearoyloxyethylthio)ethyl7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate

Sub-class III

1,2-propylene glycol bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]

Ethylene glycol bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]

Neopentylglycol bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]

Ethylene glycol bis-(3,5-di-t-butyl-4-hydroxyphenylacetate)

Glycerine-1-n-octadecanoate-2,3-bis-(3,5-di-t-butyl-4-hydroxyphenylacetate

Pentaethylthritol-tetrakis-[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]

1,1,1-trimethylolethane-tris-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate

Sorbitol hexa-[3-(3,5-di-t-butyl-4-hydroxy-phenyl)propionate]

1,2,3-butanetriol tris-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]

2-hydroxyethyl 7-(3-methyl-5-t-butyl-4-hydroxy phenyl)heptanoate

2-stearoyloxyethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate

1,6-n-hexanediol-bis[(3',5'-di-t-butyl-4-hydroxyphenyl)propionate]

The above phenolic ester stabilizers of sub-classes I, II and III aremore fully described in U.S. Pat. Nos. 3,330,859, and 3,644,482,respectively.

12. Phenolic compounds having the formula ##STR11## where x is aninteger of 1 to 2. Illustrative examples of such compounds are

Di-n-octadecyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate

Di-n-octadecyl 3-t-butyl-4-hydroxy-5-methylbenzylphosphonate

Di-n-octadecyl 1-(3,5-di-t-butyl-4-hydroxyphenyl)-ethanephosphonate

Di-n-tetradecyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate

Di-n-hexadecyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate

Di-n-docosyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate

Di-n-octadecyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate

The above di-(higher)alkyl phenolic phosphonates are more fullydescribed in U.S. Pat. No. 3,281,505.

13. Phenolic compounds having the formula ##STR12## wherein W and Q areas defined above. Illustrative examples of such compounds are

tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate

tris-(3-t-butyl-4-hydroxy-5-methylbenzyl)isocyanurate

The above hydroxyphenylalkenyl isocyanurates are more fully described inU.S. Pat. No. 3,531,483.

The above phenolic hydrocarbon stabilizers are known and many arecommercially available.

While any of the above mentioned antioxidants can be useful incombination with the ultraviolet light stabilizers of this invention,the preferred antioxidants consist of the hindered phenols in groups 1,8, 9, 10, 11, 12 and 13 as mentioned above. The most preferred hinderedphenols are those of groups 1, 9, 11, 12 and 13.

The compounds of this invention may be prepared by reacting asubstituted piperazine dione of the formula ##STR13## wherein R¹ and R²,are as defined above with a organic mono, di or tri-halo compound. Thealkylation reaction is carried out by first preparing the alkali oralkaline earth metal salt of the compound of formula II and reacting theresulting salt with the appropriate organic halide in a solvent such asdimethylformamide, isopropanol or acetone at about 75° C.

Compounds of formula II, wherein R¹ and R² form a mono cyclic ring withthe carbon to which they are attached, may be prepared by the selfcondensation of a cycloalkyl amino cyanohydrin according to theprocedure described by R. Sudo and S. Ichihera, Bull, Chem. Soc. Japan36 34 (1963) and subsequent hydrolysis as described by E. F. J. Duynsteeet al, Recueil de Chemie des Pays - Bas 87 945 (1968). Thecycloalkylamino cyanohydrin is formed by the sequential addition ofhydrogen cyanide and ammonia to a cycloalkanone as described by W. E.Noland, R. J. Sundberg and M. L. Michaelson, J. Org. Chem. 28 3576(1963). Although the above references deal specifically with thecycloalkyl case, the procedures therein have been found to be operablein the alkyl case as well, for example substitution of an alkanone suchas acetone for the cycloalkanone such as cyclohexanone in the aboveprocedure.

Examples of organic halides which can be reacted with the salts of thecompounds of formula II include organic monohalides such asmethyliodide, ethyl chloride, propyl bromide, isopropyl chloride, butylbromide, pentyl bromide, isopentyl chloride, hexyl bromide, octylbromide, dodecyl bromide, tetradecyl chloride, hexadecyl bromide,octadecyl bromide, eicosyl bromide, benzyl chloride and the like;organic dihalides such as methylene bromide, dibromoethane,1,3-dibromopropane, 1,3-dibromobutane, 1,4-dibromobutane,1,8-dibromooctane, 1,12-dichlorododecane, 1,2-dichlorooctane,1,18-dibromooctadecane, 1,20-dibromoeicosane, p-dichloroxylilene,2,3,5,6-tetramethyl-1,4-bis-chloromethylbenzene and the like; organictrihalides such as α,α',α"-trichloromesitylene,2,4,6-trimethyl-α,α',α"-trichloromesitylene, 1,2,3-tribromobutane andthe like. The preferred organic monohalide contains from 6 to 18 carbonatoms. The preferred organic dihalide contains from 2 to 12 carbon atomsand the preferred organic trihalide contains from 4 to 12 carbon atoms.

The following examples, presented for illustration and not limitation,will further serve to typify the nature of the present invention.

EXAMPLE 1 1-Aminocyclohexanecarbonitrile

In a 200 ml - 3 necked flask equipped with a stirrer, thermometer,condenser drying tube and gas inlet tube were placed 100 g (0.8 moles)of cyclohexanone cyanohydrin and the reaction mixture was cooled with anice bath to 15° C. Gaseous anhydrous ammonia was introduced to thereaction mixture through the gas inlet tube for 6 hours. The reactionwas then stoppered and allowed to stand overnight.

The next day anhydrous ammonia was again passed through the reactionmixture for 5 hours at 25° C then dry N₂ was passed through the reactionmixture to entrain any excess NH₃. The product was then dissolved in 250ml of benzene, the benzene solution washed two times with 250 ml ofwater, and the solution dried over anhydrous Na₂ SO₄. Evaporation of thebenzene yielded the product which was a slightly yellow oil.

In a similar manner, 1-aminoisobutyronitrile was prepared bysubstituting for cyclohexanone cyanohydrin an equivalent amount ofacetone cyanohydrin.

Similarly, 1-amino-2-methyl cyclohexane carbonitrile is prepared bysubstituting for cyclohexanone cyanohydrin an equivalent amount of2-methyl cyclohexanone cyanohydrin.

EXAMPLE 2 Bis-(1-cyanocyclohexyl)amine

In a 1-necked round bottomed flask equipped with a capillary nitrogeninlet and an air condenser was placed 48.2 g (0.39 moles) of1-aminocyclohexane carbonitrile. The reaction mixture was heated in anoil bath to a bath temperature of 75°-100° over 1 hour and placed undera vacuum using a water aspirator. The reaction was continued for 24hours, cooled to room temperature, the vacuum released, and thecrystalline mass was triturated with ether and filtered by suction,yielding 19.1 g of white crystals, m.p. 133°-138° C.

In a similar manner, bis(1-cyanoisopropylamine) was prepared bysubstituting for 1-aminocyclohexane carbonitrile an equivalent amount of1-aminoisobutyronitrile.

Similarly, bis-(1-cyano-2-methyl cyclohexyl) amine is prepared bysubstituting for 1-aminocyclohexanecarbonitrile an equivalent amount of1-amino-2-methyl cyclohexanecarbonitrile.

EXAMPLE 3 7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione

To 406 g of 96% H₂ SO₄ contained in a 500 ml 3-necked flask equippedwith a stirrer, thermometer and powder funnel was added with stirringand cooling, 30.0 g of powdered bis-(1-cyanocyclohexyl)amine over abouta 2 hour period. The temperature of the reaction mixture was maintainedat 0°-5° during the addition by using an ice bath. The reaction mixturewas allowed to warm to room temperature and to stir overnight. Thereaction mixture was then heated to 100° C for one hour, then cooled toapproximately 15° C and poured onto 3000 g. of ice. The aqueous mixturewas neutralized to pH 7 by the addition of approximately 800 ml of 10NNaOH. The resulting precipitate was collected by suction filtration,washed well with water, and dried in a vacuum oven, yielding a whitepowder, m.p. 155°-160° C.

In a similar manner, 2,2,6,6-tetramethyl-3,5-diketopiperazine wasprepared by substituting for bis(1-cyanohexyl)amine an equivalent amountof bis(1-cyanoisopropylamine).

Similarly, 1,9-dimethyl-7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione is prepared by substituting forbis-(1-cyanocyclohexyl)amine an equivalent amount ofbis-(1-cyano-2-methylcyclohexyl)amine.

EXAMPLE 415-n-octadecyl-7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione

To a solution of 10.0 g. (0.04 moles) of 7,15-diazadispiro [5,1,5,3]hexadecane-14,16-dione in 150 ml of anhydrous methanol in a 500 ml flaskwas added 2.6 g. of 86% KOH (0.04 moles) and the mixture was shakenuntil solution was obtained. The reaction mixture was then evaporated todryness under reduced pressure. The residue was transferred to a 300 ml3-necked flask equipped with a stirrer, thermometer, condenser withdrying tube, dropping funnel and nitrogen inlet with the aid of a smallamount of dry DMF. To the potassium imide salt, under a nitrogenatmosphere, was added 150 ml of dry DMF. To the stirred solution wasadded dropwise a solution of 13.3 g. (0.04 moles) of n-octadecyl bromidein 50 ml of DMF. The reaction mixture was heated slowly to 75° C andheld at that temperature for 3 hours. The reaction mixture was cooledand allowed to stand at room temperature overnight. The reaction mixturewas then taken up in 500 ml ether, the ether solution washed well withwater, dried over anhydrous Na₂ SO₄ and evaporated under reducedpressure. The residue, which crystallized on standing, wasrecrystallized from methanol yielding 14.3 g. of white needles as theproduct, m.p. 39°-40° C.

By following the above procedure, and substituting for then-octadecylbromide an equivalent amount of:

a. benzyl chloride

b. 2,3,5,6-tetramethyl-p-dichloroxylilene

c. 1,12-dibromdodecane

d. 1,3,5-trimethyl-2,4,6-trischloromethylbenzene

e. 1,8-dibromooctane

f. 1,4-dibromobutane

g. methyliodide

h. octyl bromide

i. methylene dibromide

j. 1,16-dibromohexadecane

there is respectively obtained the following compounds:

a. 15-benzyl-7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione, m.p.91°-94° C

b. 15,15'-(2",3",5",6"-tetramethyl p-xylilidenyl)bis(7,15-diazadispiro[5,1,5,3]hexadecane14,16-dione), m.p. 253°-257° C

c. 15,15'-n-dodecanemethylenebis(7,15-diazadispiro[5,1,5,3]hexadecane14,16-dione), m.p. 100°-103° C

d. 15,15',15"-(2,4,6-trimethylα,α',α"-mesitylidene)tris-(7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione,m.p. 236°-240° C

e. 15,15'-n-octamethylenebis(7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione)

f. 15,15'-tetramethylenebis(7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione, m.p. 178°-181° C

g. 15-methyl-7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione, m.p.122°-126° C

h. 15-n-octyl-7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione)

i. 15,15'-methylenebis(7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione), m.p. 209°-215° C

j. 15,15'-hexadecamethylenebis(7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione), m.p. 82°-87° C.

EXAMPLE 5

By essentially following the procedure of Example 4 and substituting for7,15-diazadispiro [5,1,5,3]hexadecane-14,16-dione in each compoundprepared in the example an equivalent amount of2,2,6,6-tetramethyl-3,5-diketopiperazine, there is respectively obtainedthe following compounds:

a. 4-n-octadecyl-2,2,6,6-tetramethyl-3,5-diketopiperazine; m.p. 52°-54°C

b. 4-benzyl-2,2,6,6-tetramethyl-3,5-diketopiperazine; m.p. 80°-84° C

C.4,4'(2",3",5",6"-tetramethyl-p-xylilidenyl)bis(2,2,6,6-tetramethyl-3,5-diketopiperazine

d. 4,4'-(n-dodecamethylene)bis(2,2,6,6-tetramethyl3,5-diketopiperazine;m.p. 73°-75° C

e. 4,4'-(2,4,6-trimethylα,α',α",-mesitylidene)tris(2,2,6,6-tetramethyl-3,5-diketopiperazine)

f. 4,4'(n-octamethylene)bis(2,2,6,6-tetramethyl-3,5-diketopiperazine)

g. 4,4'(tetramethylene)bis(2,2,6,6-tetramethyl-3,5-diketopiperazine)

h. 4-methyl-2,2,6,6-tetramethyl-3,5-diketopiperazine

i. 4-n-octyl-2,2,6,6-tetramethyl-3,5-diketopiperazine

EXAMPLE 6

By essentially following the procedure of Example 4 and substituting for7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione and the organic halidesused in the example, an equivalent amount of1,9-dimethyl-7,15-diazadispiro[5,1,5,3]hexadecane14,16-dione andn-octadecylbromide there is obtained15-n-octadecyl-1,9-dimethyl-7,15-diazadispiro[5,1,5,3]hexadecane.

EXAMPLE 7 Artificial Light Exposure Test

Deterioration of most polymers caused by ultraviolet light is so slow atambient temperatures, even in the absence of stabilizers, that testingof the effects of stabilizers generally must be conducted either athigher temperatures or in an accelerated artificial light exposuredevice in order to yield results in a convenient period of time. Thetest conducted on polymers using an artificial light exposure device isdescribed below:

a. Sample Preparation

5 mil Film -- Unstabilized polypropylene powder (Hercules Profax 6501)is thoroughly blended with the indicated amounts of additives. Theblended material is then milled on a two roll mill for 5 minutes at 182°C. The milled sheet is then compression molded at 220° C into 5 milthick film under a pressure of 175 psi and water cooled in the press.

b. Testing Method

This test is conducted in a FS/BL unit, basically of the AmericanCyanamid design, which consists of 40 tubes of alternating fluorescentsun lamps and black lights (20 of each). The 5 mil sample films aremounted on 3 × 2 inches IR card holders with 1/4 × 1 inches windows andare placed on a rotating drum 2 inches from the bulbs in the FS/BL unit.The time in hours is noted for the development of 0.5 carbonylabsorbance units as determined on an Infrared Spectrophotometer. Thedevelopment of carbonyl functional groups in the polymer is proportionalto the amount of degradation caused by the ultraviolet light exposure.

The test results reported below were obtained according to theprocedures described above. The amounts of the additives are expressedin weight percent based on the weight of the polymer.

                  Table I                                                         ______________________________________                                                                Time in Hours                                                                 to .5 Carbonyl                                        Formulation*            Absorbance Units                                      ______________________________________                                        .5% 15-n-octadecyl-7,15-diaza-                                                dispiro [5,1,5,3]hexadecane-14,                                               16-dione                855                                                   .5% 15-benzyl-7,15-diazadispiro                                               [5,1,5,3]hexadecane-14,16-dione                                                                       725                                                   .5% 15,15'-(2",3",5",6"-tetramethyl                                           p-xylilidenyl)bis(7,15-diazadispiro                                           [5,1,5,3]hexadecane 14,16-dione                                                                       340                                                   .5% 15,15'-n-dodecanemethylene bis                                            (7,15-diazadispiro[5,1,5,3]hexadecane                                         14,16-dione)            680                                                   .5% 15,15'-n-octamethylene bis (7,15-                                         diazadispiro 5,1,5,3]hexadecane 14,16-                                        dione)                  620                                                   .5% 15,15',15"-(2,4,6-trimethyl-α,α',α"-                    mesitylidene)tris(7,15-diazadispiro                                           [5,1,5,3]hexadecane-14,16-dione                                                                       410                                                   .5% 15,15'-tetramethylene bis(7,15-                                           diazadispiro[5,1,5,3]hexadecane-14,16-                                        dione)                  713                                                   .5% 4-n-octadecyl-2,2,6,6-tetramethyl-                                        3,5-diketo piperazine   830                                                   .5% 15-methyl-7,15-diazadispiro[5,1,5,3]                                      hexadecane-14,16-dione  750                                                   .5% 15-n-octyl-7,15-diazadispiro                                              [5,1,5,3]hexadecane-14,16-dione                                                                       1170                                                  0.5% 4-benzyl-2,2,6,6-tetra-                                                  methyl-3,5-diketopiperazine                                                                           800                                                   0.5% 4,4'-n-dodecamethylene bis                                               (2,2,6,6-tetramethyl-3,5-diketo-                                              piperazine)             1040                                                  0.5% 15,15'-methylene bis(7,15-                                               diazadispiro[5,1,5,3]hexadecane-                                              14,16-dione)            720                                                   0.5% 15,15'-hexadecamethylene bis                                             (7,15-diazadispiro[5,1,5,3]                                                   hexadecane-14,16-dione) 1005                                                  Control*                225                                                   ______________________________________                                          *Each of the samples tested and the control contains 0.2% of                 (di-n-octadecyl(3,5-di-t-butyl-4-hydroxybenzyl) phosphonate which is an       antioxidant which prevents oxidative degradation of polypropylene.       

Other hindered phenolic antioxidants may be used in place ofdi-octadecyl(3,5-di-t-butyl-4-hydroxybenzyl)phosphonate in the abovementioned compositions for example, di-n-octadecylα-(3-t-butyl-4-hydroxy-5-methylbenzyl)malonate,2,4-bis-(n-octylthio)-6-(3,5-di-t-butyl-4-hydroxyanilino)-1,3,5-triazine,octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate,pentaethylthrito-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate respectively.

EXAMPLE 8

a. A composition comprising acrylonitrilebutadiene-styrene terpolymerand 1% by weight of 15,15'-n-dodecamethylenebis(7,15-diazadispiro[5,1,5,3]hexadecane 14,16-dione) resistsembrittlement due to exposure to ultraviolet light longer than one whichdoes not contain the stabilizer.

b. A composition comprising a polyurethane prepared from toluenediisocyanate and alkylene polyols and 1.0% by weight of15-benzyl-7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione is morestable to sunlight, fluorescent sunlamps, black lights and fluorescentlights than the unformulated polyurethane.

c. A composition comprising a polycarbonate prepared from bisphenol-Aand phosgene and 1% by weight of4-n-octadecyl-2,2,6,6-tetramethyl3,5-diketopiperazine resistsdiscloloration due to exposure to ultraviolet light longer than onewhich does not contain the stabilizer.

d. A composition comprising a polyester (polyethyleneterephthalate) and0.2% by weight of15,15'-(2",3",5",6"-tetramethyl-p-xylilidenyl)bis(7,15-diazadispiro[5,1,5,3]hexadecaneresists discoloration due to exposure to ultraviolet light longer thanone which does not contain the stabilizer.

e. A composition comprising polymethylmethacrylate and 0.25% by weightof15,15'-(2",3",5",6"-tetramethyl-p-xylilidenyl)bis(7,15-diazadispiro[5,1,5,3]hexadecaneresists discoloration due to exposure to ultraviolet light longer thanone which does not

EXAMPLE 9

a. A stabilized linear polyethylene is prepared by incorporating therein0.5% by weight of 4-benzyl-2,2,6,6-tetramethyl-3,5-diketopiperazine. Thestabilized compositions resist embrittlement due to exposure toultraviolet light longer than one which does not contain the stabilizer.

b. A stabilized polyamide (nylon 6,6) is prepared by incorporatingtherein 0.1% of 15,n-octadecyl-7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione. The light stability of the stabilized composition is superiorto that of an unstabilized polyamide.

c. A stabilized polyphenylene oxide polymer (prepared by polymerizing2,6-dimethylphenol) is prepared by incorporating therein 0.5% by weight15,15'-(2",3",5",6"-tetramethyl-p-xylilidenyl)bis(7,15-diazadispiro[5,1,5,3]hexadecane14,16-dione. The stabilized compositions resist embrittlement due toexposure to ultraviolet light longer than one which does not contain thestabilizer.

d. A stabilized crystalline polystyrene is prepared by incorporatingtherein 0.1% by weight of4,4'-(2,4,6-trimethyl-α,α',α"-mesitylidene)tris-2,2,6,6-tetramethyl-3,5-diketopiperazine.The stabilized compositions resists embrittlement due to exposure toultraviolet light longer than one which does not contain the stabilizer.

EXAMPLE 10

High impact polystyrene resin containing elastomer (i.e.,butadiene-styrene) is stabilized against loss of elongation propertiesdue to exposure to ultraviolet light by incorporation of 0.3% by weightof 15-n-octadecyl-7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione.

The unstabilized resin is dissolved in chloroform and the stabilizerthen added, after which the mixture is cast on a glass plate and thesolvent evaporated to yield a uniform film which, upon drying, isremoved and cut up, and then pressed for 7 minutes at a temperature of163° C and a pressure of 2,000 pounds per square inch into a sheet ofuniform thickness (25 mil). The sheets are then cut into stripsapproximately 4 × 0.5 inches. A portion of these strips is then measuredfor percent of elongation in the Instron Tensile Testing Apparatus(Instron Engineering Corporation, Quincy, Massachusetts). The remainingportion of the strips are placed in an FS/BL chamber according toExample 6 (b) except that the time to 50% reduction in elongation ismeasured. The stabilized polystyrene resin retains its elongationproperty longer than the unstabilized resin.

Similar results are obtained when an equivalent amount of the followingstabilizers are used in place of the above mentioned stabilizer.

a. 0.1% by weight of 15,15', 15"-(2,4,6-trimethyl-α, α',α"-mesitylidene)tris(7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dion

b. 0.2% by weight of15,15'-n-octamethylenebis(7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione)

c. 1.0% by weight of15-methyl-7,15-diazadispiro[5,1,3]hexadecane-14,16-dione

d. 0.1% by weight of4-n-octadecyl-2,2,6,6-tetramethyl-3,5-diketopiperazine

e. 0.1% by weight of 4,4'(2", 3", 5",6"-tetramethyl-p-xylilidenyl)bis(2,2,6,6-tetramethyl-3,5-diketopiperazine

f. 0.5% by weight of4,4'(n-octamethylene)bis(2,2,6,6-tetramethyl-3,5-diketopiperazine

g. 1% by weight of 4-n-octyl-2,2,6,6-tetramethyl-3,5-diketopiperazine

h. 0.5% by weight of15-n-octadecyl-1,9-dimethyl-7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione.

Antioxidants may also be incorporated into each of the above mentionedcompositions for example, di-n-octadecyl-α,α'-bis(3-t-butyl-4-hydroxy-5-methylbenzyl) malonate2,4-bis(4-hydroxy-3,5-di-t-butylphenoxy)-6-(n-octylthioethylthio)-1,3,5-triazine,2,4-bis(3,5-di-t-butyl-hydroxyphenoxy)-6-(n-octylthio)-1,3,5-triazinedi-n-octadecyl 3,5-di-t-butyl-4-hydroxybenzyl phosphonate and octadecyl3(3', 5"-di-t-butyl-4-hydroxyphenyl)propionate respectively.

EXAMPLE 11 Outdoor Exposure Tests

The additives were solvent blended onto polypropylene powder (HerculesProfax 6501) in the indicated amounts, the powder was agitated for 5minutes in a Kitchen Aid planetary mixer and the powder mixture wasdried in a vacuum oven at a vacuum of 30 inches of water overnight.

The polypropylene powder containing the additives was extrudercompounded at 232° C into pellets, and the pellets were melt spun at260° C into 15 denier monofilaments using a 10 mil orifice monofilamentspinerett. The monofilaments were air cooled and oriented at a 4:1 ratiobetween hot (125° C) and cold godets and wound onto a fiber spool. Themonofilament was mounted on wooden exposure frames and exposed at 45°south direct weathering inland in Florida. Samples were removed fromexposure periodically and tensile tested on the Instron Table Modeltensile tester using fiber grips. The kilolangleys to 50% retention oftensile strength of the monofilament were determined.

The results indicated below show the number of kilolangleys (KL) to 50%retention of tensile strength. A Langley is a measure of energy in theultraviolet region to which the samples have been exposed.

                  Table III                                                       ______________________________________                                                             KL to 50% Retention                                      Formulation*         of Tensile Strength                                      ______________________________________                                        0.5% of 15-n-octadecyl-7,15-                                                  diazadispiro[5,1,5,3]hexadecane-                                              4,16-dione           69                                                       0.5% of 15-benzyl-7,15-diaza-                                                 dispiro[5,1,5,3]hexadecane-                                                   14,16-dione          81                                                       Control*             36                                                       ______________________________________                                          *Each of the sample tests and the control contain 0.5% of the antioxidan     di-octadecyl(3,5-di-t-butyl-4-hydroxybenzyl)phosphonate and 0.1% of the       buffer calcium stearate.                                                 

What is claimed is:
 1. A compound of the formula ##STR14## wherein R¹and R² are together with the carbon to which they are bound form acyclopentyl or cyclohexyl ring, which is unsubstituted or substitutedwith a methyl group, andR³ is benzyl.